Investigations

Review

Minutes of 2008-Mar-10 S5 QPipeline Review Teleconference

This telecon was rescheduled from March 6, 2008. The call started at 11:00 Eastern.

Attendance

Shourov Chatterji, Jonah Kanner, Dave Reitze

Minutes by Jonah Kanner.

Announcements

Discussion

Dave: should we look again at coincidence window lengths, as suggested
by erik?
Shourov: no, i think it's fine. Erik's concern was based on how other
pipelines do coincidence. for example, a white noise burst with a 1 s
duration could have peaks at different times at different detecotors. so,
clustering algorithms might fail. i'm of the opinion that clusters should
not be used for testing coincidence. If something is 1 s long, all of those
tiles are tested for coincidence.
Corrected link:
ldas-jobs.ligo.caltech.edu/~shourov/s5qreview/production_playground/old/H1H2L1/window/
Reviewing these tests, it seems clear that the 10 ms window is fine.
Dave: Coming back to white noise burst waveforms, a long waveform does show increased efficiency
as the window increases: why are they "worst case"?
Shourov: Because they are long duration and high bandwidth, so hard for coincidence
Dave: what does "minor improvement" mean?
Shourov: Scroll down. It is of order 1 more injection out of ~38 injections x multiple amplitude
scales
Dave: Perhaps you could quantify the rate of "accidental coincidences" ?
Shourov: hmmm...that might be hard - it's probably wave-form dependant.
Shourov: Try adding /report.txt to the web address
Dave: there are 100's in some burst tables, but not others
Shourov: it seems consistent with the frequency span of the waveforms: more freq. space
suggests more accidental coincidences.
dave and jonah: ok, we're convinced this is ok
Shourov: status: did trigger production for h1h2 zero lag. if we want to test zero-lag background
h1h2 time-shifted with L1
jonah: does that run a danger of 'peeking' in the box?
shourov: well - maybe. if you do limited time lags, it might be ok. one reason i moved things
around is to clean up
go to ~shorov/s5qreview/triggers/s5
shorov: these are various levels of trigger posproduction. step 5 is coincidence.
go to 5/H1H2L1/RAW
some interesting things are that for high scale, you get more triggers than you did for singe detector
H1L1 and H2L1 are options, but they are low priority.
Re-mapping is step 6 that is in progress
One issue in previous versions of code is that i was using H1H2 coherent as measure of significance
- one consequence was that mainly H1 level triggers were left over, and those depended very
little on time slides - so time slides were not independent
Now that significance is based partly on correlated energy, as you time-slide time shifts are
more independant, and you can use the time-shifts to train the re-mapping
The only worry is that real GW's would show up in time slides, and so devalue themselves
I've played around to convince myself that the issue is better - i hope to show that, using the
playground day, the correlated energy is better with the re-mapping.
Shourov: go to /s5qreview/old/scatter/likelihood
here we see some notes about a bayesian type approach
the problem is that the probabities we get depend on the probabilities we inject
the nice property is that in coherent/correlated space, injections lie on a line
so, as a measure of 'how GW like', we can use a measure of how far from line in
hard-corr space
So, i think that's we're things stand. the final step is defining this re-mapping
and then i should be ready to open the box.
Dave and Jonah: we need time to digest this
http://ldas-jobs.ligo.caltech.edu/~shourov/s5qreview/old/scatter/likelihood
shourov: ok, well, this is what i'm working on now as well.
dave: should we meet this thrusday??
Shourov: i will likely be travelling on thurday
dave: ok - then we'll wait to hear from you.